Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Politics : CONSPIRACY THEORIES -- Ignore unavailable to you. Want to Upgrade?

To: sea_urchin who wrote (104)	1/22/2005 6:28:34 AM
From: GUSTAVE JAEGER	Read Replies (1) \| Respond to of 418

Re: Come on, don't kid yourself. The explosions were far too deep under the water... Well, I guess you're right... the deeper the explosions the better for the shock-wave's strength... Anyway, here's an interesting paper on underwater explosions --although it's primarily concerned with conventional explosives (ie, not nuclear), the hydrodynamics remain relevant: TRANSMITTING MEDIA Explosive shooting is conducted in solids beneath the water surface for removal or demolition uses. The work accomplished by the gas expansion phase is energy consumed. Less gas energy can be converted to P-waves to enter the water, since the gas bubble will not pulsate as it rises. Conversely, the shock energy rapidly disturbs all surrounding environs. The P(r,t) for the first arrival must be resolved by the properties of the blasted medium, blast geometry, and wave transmissions across boundary surfaces. The propagation of waves across surfaces between media has been developed by text authors, such as Kinsler and Frey (1950) and Grant and West (1965). *Oriard (1985) shows that the energy transmitted to water from rock of specified properties varies from 0.0 to 0.37 of the total shock energy for varied angles of incidence (Figure 2.2).[]** Oriard (1985) shows that for land-based blasting adjacent to a water body the pressure wave's amplitude "is about 1/40 to 1/400 of" that amplitude which would be calculated for perpendicular (0.°) incidence between water and ideal rock. Shock-wave energy would be considerably greater when the blasted medium is directly beneath the water column. In this latter case, 30% to 37% (for 30° down to 0° incidence, respectively) of the generated energy enters the water. Blasting would not usually be accomplished in weak material of low P-wave velocity and Elastic Modulus. The solid's properties would almost always be significantly greater than water's, thus the pressures and energies should be comparable to those of Figure 2.2, in general. At large incidence angles (greater lateral distances from the blast within a submerged solid), less energy enters the water from the solid, but the water-borne energies from directly above the shot persist in the water beyond the critical refraction angle. For the case cited by Oriard in Figure 2.2, this angle is 19.1° (Grant and West 1965). The water column acts as a wave guide at incident angles within the water greater than the refraction angle while continuing to receive energy from the solid. In other words, some energy at large lateral distances from the shot is captured and retained by the water column. Another consideration of the shock wave from a solid-confined blast is the direction of the explosive's detonation. Initiation of shots is normally at the deepest part of the explosive charge. The detonation begins near the bottom of the boring and continues to propagate up the explosive column toward the surface. The detonation wave is focused toward a narrow cone in the direction of travel. Less shock energy is transmitted radially and only a small percentage of shock disturbance emanates opposite the detonation direction (Konya and Walter 1985). The shock wave from the completed upward detonation is focused toward the water column. Thus, the strongest intensity of shock energy in the water column is directly above the blast for a confining solid. The shock energy crossing the boundary, which is generally normal to the explosive's placement borings, into the water is the largest (0.37 for the cited example) of all the transmission angles. Blasting in a solid beneath the water surface allows gas energy to be released to the water. The extreme cases for gas energy production are comparable to two scenarios: the blast detonated in the water column (maximum gas energy contribution) and the explosive shot within a material of sufficient strength to retain the blast products. There is no gas energy component for a mid-water explosion, if the explosion occurs within a container that totally contains the reaction gases. There would also be no oscillating gas bubble since the container retained the expansion products. All the work (in actual production blasting) accomplished by the detonation's gases in moving the solid mass is work that cannot contribute to bubble oscillation energy release in the water column. Premature venting of the explosives' gases reduces the displacement of the mass and imparts this gas energy to the water column. Having sufficient stemming (the granular filling from the top of the blasting material to the top of the borehole) length eliminates the early release of the detonation's gases. [...] 216.239.59.104 [] My guesstimate() was correct: an underwater earthquake/explosion will transmit a maximum 37% of its energy to the above water mass/column... I guess that's why US geonerds were eager to "upgrade" the initial M6.4 measure to a M9 seism.... (*) Message 20937052